Brake System Damping Device

ABSTRACT

A brake system damping device includes a first chamber on which hydraulic pressure is to be applied, a second chamber with a compressible medium located therein, and a first separating element configured to separate the first and second chambers. The damping device further includes a third chamber with a compressible medium located therein and a second separating element configured to separate the second and third chambers. The second and third chambers are connected in a medium-conducting manner via a passage in the second separating element. The first separating element is configured to move a closure element to close the passage when the hydraulic pressure in the first chamber has reached a predefined pressure value. The first and second separating elements form an assembly in which the first and second separating elements extend along an axis and the first separating element is covered radially on the outside by an envelope surface.

This application claims priority under 35 U.S.C. § 119 to patentapplication no. DE 10 2019 208 406.0, filed on Jun. 8, 2019 in Germany,the disclosure of which is incorporated herein by reference in itsentirety.

BACKGROUND

The disclosure relates to a brake system damping device with a firstchamber on which hydraulic pressure is to be applied and a secondchamber in which a compressible medium is located, and a firstseparating element for separating the first chamber from the secondchamber.

Brake systems, in particular hydraulic brake systems, serve to slow downa driving speed of vehicles such as cars and HGVs. During operation ofsuch brake systems, various dynamic effects occur, among other things,pressure fluctuations in lines and chambers present there which lead tovibrations or pulsations and as a result to undesirable noises andvibrations. In order to minimize such vibrations or achieve a dampingeffect in the case of these vibrations, brake system damping devices,also referred to below as dampers, are used at one or more installationlocations in the brake system. These dampers comprise a first chamber inwhich a hydraulic pressure is to be applied. The chamber is in principlea type of container. The pressure is in principle the result of a forceacting on a surface. A force is transmitted hydraulically, i.e. via apressurized fluid, in the dampers.

Dampers are known with a separating element which separates the chamberinto a first chamber, in which a liquid or a fluid is located, and asecond chamber, in which a compressible medium, generally in the form ofa gas, is located. The volume of a chamber of a deformable container, inwhich a gas is located, is known to reduce if an elevated pressure isexerted on this container from the outside. The volume of the secondchamber is equally also reduced by means of the separating element if ahydraulic pressure is applied on the first chamber.

If this pressure once again drops, the volume of the gas and thus of thesecond chamber correspondingly also increases again. The second chambertherefore acts like a pneumatic spring, also referred to as a gasspring. How soft or hard this gas spring damps is dependent on the gasvolume of the second chamber. The greater the gas volume, the softer thedamping.

During a braking operation, a vehicle driver steps on a brake pedalwhich passes through a pedal travel. This pedal travel is directlyrelated to the gas volume of the second chamber which is relevant here.The greater the gas volume, the longer the pedal travel. The positiveeffect of soft damping thus runs counter to the negative effect of alarge pedal travel length.

The object on which the disclosure is based is to provide a device forvibration damping in a brake system with improved damping properties.

SUMMARY

According to the disclosure, a brake system damping device is createdwith a first chamber on which hydraulic pressure is to be applied and asecond chamber in which a compressible medium is located, and a firstseparating element for separating the first chamber from the secondchamber. The object is achieved according to the disclosure in that thebrake system damping device has a third chamber in which thecompressible medium is also located and a second separating element forseparating the second chamber from the third chamber. The second chamberis connected to the third chamber in a medium-conducting manner by meansof a passage configured in the second separating element. Moreover, aclosure element is to be moved with the first separating element, bymeans of which closure element the passage is to be closed, as soon as,in the first chamber, the hydraulic pressure has reached a predefinedpressure value.

The third chamber therefore contains, like the second chamber, thecompressible medium which is preferably configured with a gas andparticularly preferably with air. The second separating elementsseparates the third chamber from the second chamber, wherein the twochambers, however, initially remain connected by means of themedium-conducting passage. The passage or the link is preferablyconfigured with a simple bore and can be closed by means of the closureelement of the first separating element. The closure element ispreferably simply a surface region on the surface of the firstseparating element. This closure element only closes the passage when anadequate hydraulic pressure for this is present in the first chamber.Concretely, the first separating element is in particular deformed fromthe predefined pressure value to such an extent that it is then appliedon the second separating element. The second separating elementtherefore preferably forms a stop for the closure element.

As a result of the closed passage, the third chamber is then uncoupledfrom the second chamber and is thus no longer available for theremaining damper. Only the medium volume in the second chamber remainsfor the further damping action above a predefined pressure value. Thisis thus relatively small as a result of the first separating elementdeformed in the direction of the second separating element. The damperaccording to the disclosure thus only still has a lower elasticity anddamping action since the second chamber is barely able to still take upvolume. The advantageous effect is, however, that thus a pedal travel orthe travel of a brake pedal of the brake system is no longersignificantly lengthened in the event of an actuation by means of avehicle driver. Upon closure of the passage, the first separatingelement particularly advantageously even bears completely against theinner wall of the second chamber, including the side of the secondseparating element facing the second chamber, so that the second chamberentirely disappears or no longer has any volume. The pedal travel isthen no longer lengthened in the first place from the predefinedpressure value. The damping action which is also reduced as a result ofthis is acceptable since the pressure range which is relevant for thedamping lies below the predefined pressure value.

The pressure value is therefore preferably selected or predefined sothat it represents the upper threshold value of a pressure range whichis relevant for the damping. The respective volumes of the second andthird chamber are preferably adjusted to the relevant pressure range andthe desired elasticity or damping action of the damper. In thisadvantageous manner, the damper connects the large elasticity of thelarge medium volume in the pressure range relevant for the damping witha restriction of the volume which can be taken up by the first chamberabove this pressure range. In other words, there is no directrelationship any more between the displaced volume of brake medium andthe medium volume used for the damping. The damper thus offersoutstanding damping properties in the case of a short pedal travel.

A further advantage of the disclosure is that the pressure in the closedoff third chamber is significantly lower than the pressure in the secondchamber without passage to a further chamber, i.e. in the case of theprior art. Undesirable effects are reduced as a result of this. On onehand, in the case of low pressure, the permeation through the firstseparating element is reduced, on the other hand, the temperature of themedium at low pressure is not so high, as a result of which materialaging of the first separating element is delayed.

Furthermore, according to the disclosure, the first separating elementand the second separating element are to be preassembled to form anassembly in which the first and second separating elements extend alongan axis and the first separating element is covered radially on theoutside at least in certain portions by means of an envelope surface.The envelope surface is in this case in particular of rigid or stiffform, whereas the first separating element is flexible or elastic.

By means of the envelope surface of this type, a sliding surface isformed on the outside on the first separating element, along whichsliding surface the assembly that is formed can advantageously beinserted and mounted into an associated housing. The feed and mountingof the assembly formed according to the disclosure can thus be automatedin an effective manner, and then performed automatically. Customeracceptance and market opportunities of vehicles which are fitted withthe brake system damping device according to the disclosure can besignificantly improved with the aid of the listed technical advantages.

The envelope surface may be formed as a coating on the first separatingelement itself. It is advantageous according to the disclosure if theenvelope surface is formed by a hollow cylindrical sleeve, which is inparticular pushed onto the first separating element. The sleeve forms aninitially separate component which is to be pushed onto the assemblyformed from at least first and second separating element. Although thisgenerates additional outlay, this outlay is however outweighed by theadvantages thereby achieved, of improved handlability and mountabilityof the assembly. The sleeve is in this case particularly preferablycomposed of metal, and in particular produced as a thin-walledsheet-metal part and by means of deep-drawing.

The envelope surface, in particular sleeve, is furthermoreadvantageously configured with a radially external interference fit forpressing into a housing which receives the assembly. A positionallyaccurate and at the same time force-fitting, stationary position of theassembly in the housing is to be produced by means of the interferencefit. At the same time, the interference fit may also be configured so asto be substantially or else completely fluid-tight.

In one refinement of the disclosure, it is also advantageous that theenvelope surface is configured with a radially internal first insertionbevel for facilitated pushing of the envelope surface onto the firstseparating element and/or with a radially external second insertionbevel for facilitated insertion of the envelope surface into a housingwhich receives the assembly. By means of the insertion bevels, it is inparticular possible for the mounting of the brake system damping deviceaccording to disclosure to be automated considerably less expensivelyand in a more reliable manner in terms of a process.

The envelope surface is furthermore preferably configured with aradially external shoulder for support on a housing which receives theassembly. The shoulder may advantageously serve as a stop surface and/oras an interference-fit seat for the assembly mounted into the housing.

The second separating element is preferably supported by a cover, bymeans of which the third chamber is simultaneously delimited. Here, thesecond separating element is advantageously held preceding from or inthe cover by means of an interference fit. The cover is then provided asa closure for a brake system with the brake system damping deviceaccording to the disclosure and enables flexible access to the brakesystem. As a result of this, a simple replacement of the first or secondseparating element may also be possible. Moreover, brake system dampingdevices which hitherto only use a chamber between the cover and anelastic separating element for damping can be retrofitted with thesecond separating element.

By virtue of the fact that the third chamber is formed by means of thesecond separating element and a cover and the second separating elementis retained on the cover by means of an interference fit in afluid-impervious manner, a connection which is impervious over theperiod of operation and can at the same time be produced advantageouslyin terms of assembly is created between the cover and the secondseparating element. This ensures in particular that the third chamberformed behind the second separating element is permanently imperviousand no fluid can travel out of it to the outside past the cover.

The second separating element preferably extends along an axis and theinterference fit is formed radially on the outside on the secondseparating element. Such interference fit has a preferably large surfaceand thus a large sealing-off region. Moreover, with such an interferencefit, an advantageous material combination of a cover composed of metaland a second separating element composed of plastic can be selected.

If the second separating element extends along an axis, it isfurthermore advantageous that the second separating element also has ashoulder which is substantially radially directed against which thefirst separating element bears in a sealing manner. A hydraulic forceacts in the axial direction and thus transverse to the orientation ofthe shoulder on the radially directed shoulder in the case of a pressureincrease in the first chamber. This hydraulic force pushes a firstseparating element bearing against the shoulder substantiallyperpendicularly against the shoulder so that the first separatingelement is pressed on there advantageously additionally in a sealingmanner.

Building on this, the second separating element is preferably fullyenclosed by the cover and the first separating element. As a result ofthis, the second and third chamber with the contained medium volume areadditionally sealed off. Complete enclosure of the second separatingelement also means that the combination of these three components doesnot differ externally from a combination only of cover and firstseparating element. As a result of this, the configuration of the secondseparating element is independent of the further brake system. Even aremoval of the second separating element from the damper is thuspossible preferably if a larger medium volume is required.

It is furthermore advantageous if the first separating element has anannular sealing bead with which it bears against the second separatingelement and in particular against the cover which supports the secondseparating element in a sealing manner. Such a sealing bead then forms acentral sealing element by means of which both the first as well as thesecond and third chamber are advantageously delimited from one another.Such a solution is furthermore particularly installation space-savingsince three sealing points are realized with only one sealing element.

In the case of a further advantageous further development of thedisclosure, the first separating element is formed in one piece with theclosure element. In one piece means that two elements, here the firstseparating element and the closure element, are formed in one piece oras one part. This has the advantage of simple assembly and low-costproduction.

In the case of a next advantageous further development of thedisclosure, the first separating element is configured with a diaphragm,preferably with a roller diaphragm. Diaphragms are to be understood herein principle as sealing elements which, as elastic, movable separatingwalls or separating elements, separate two chambers hermetically fromone another. Roller diaphragms are especially provided only forone-sided pressure loading in the direction of a loop inside ordiaphragm head depression. Only a negligibly low inherent rigidity and alow degree of resistance to elastic deformation of roller diaphragmsoppose changes in volume. Roller diaphragms are therefore particularlywell suited as a separating element for the brake system damping deviceaccording to the disclosure as a result of their shaping.

Advantageously, the first separating element is produced from anelastomer, preferably from ethylene propylene diene rubber. Elastomersare plastics which are dimensionally stable, but elastically deformable.These plastics can therefore deform under tensile and compressive load,but subsequently return to their original, undeformed configuration.Elastomers are thus materials which are particularly well suited forseparating elements within the meaning of this disclosure, such as, forexample, for the roller diaphragm described above.

The elastomer must retain its elasticity and must not swell up norshrink excessively. A suitable elastomer must therefore be used for themedium to be sealed off. Ethylene propylene diene rubber, also referredto in short as EPDM, is an elastomer which is resistant to brake mediumand therefore is particularly suitable for use in the brake systemdamping device according to the disclosure.

Moreover, the predefined pressure value is according to the disclosureadvantageously predefined with a value between 0 and 30 bar, preferablybetween range 3 and 10 bar, and particularly preferably with 5 bar. If abrake system applies a pressure of approximately 60 bar on an associatedwheel of a vehicle, this reliably brings about a locking of the wheel.However, only a significantly lower, limited pressure range is relevantfor vibration and pulsation damping in brake systems. In the case of areached pressure value of approximately 5 bar, the undesired vibrationor pulsation is already adequately damped. The pressure value shouldtherefore be set particularly advantageously to this value.

The passage is furthermore preferably formed with an open-poredmaterial. A material is open-pored if it contains pores which preventthe penetration of fluids, but allows the escape or penetration ofgasses. One can talk about a breathable material. The pores would alsobe closed after bearing against of the first separating element, such asdifferently configured passages, such as, for example, bores. Theadvantage of the open-pored material, however, lies in the fact that nofluid can penetrate into the third chamber. The brake system would thushave additional protection against brake fluid running out of the brakesystem, for example, if the first separating element is damaged orleaking.

Moreover, several passages are preferably provided in the secondseparating element. These passages ensure a quicker distribution of themedium from the second into the third chamber during the brakingprocess. As a result of this, the elasticity of the entire medium volumecan be better exploited.

In a further advantageous embodiment, the third chamber is divided intoseveral sub-chambers which are connected in each case to the secondchamber by means of a passage in a medium-conducting manner. The severalsub-chambers enable higher flexibility in terms of the use only of asingle third chamber. The passages to the individual sub-chambers arethus preferably closed consecutively by means of the first separatingelement, as a result of which the damping action is gradually reduced,and not completely and suddenly in the case of one predefined pressurevalue. Moreover, a variable number of sub-chambers and thus a variablemedium volume can be used by means of closing passages and making themavailable again. This facilitates the adjustment of the damper to therelevant pressure region and the desired elasticity.

Moreover, further embodiments are advantageous which make the brakesystem damping device even more efficient or supplement it withalternative embodiments.

The compressible medium which is contained in the second and thirdchamber is thus preferably configured as a gas and particularlypreferably as air. Air is easily available, can be used and compressedwithout cost, and is thus highly suitable for use in the brake systemdamping device according to the disclosure.

The medium volumes or the second and third chamber are alternatively andadvantageously produced or created by means of a combination of severalturned, cold-formed or deep-drawn parts. Turned parts are componentswith a circular cross-section, cold-formed parts are closure componentsand deep-drawn parts are body components of vehicles. All of thesecomponents are therefore easy to procure in the automotive sector andare given a new purpose by means of the disclosure.

The brake system damping device is furthermore preferably provided foruse in vehicle dynamic controls and/or external power brake systems. Avehicle dynamic control or Electronic Stability Program, also referredto as ESP, is an electronically controlled driver assistance system fora motor vehicle which helps stop the motor vehicle from careering out ofcontrol by targeted braking of individual wheels. An external powerbrake system is operated by means of externally generated force. Forexample, an electrohydraulically activated brake is an external powerbrake in the case of which the activation energy comes from a hydraulicpressure accumulator which is charged by a pump.

In one advantageous embodiment, the brake system damping device has arib structure which supports the second separating element and passesthrough the third chamber in particular with a structure end side and atleast one structure rib. The rib structure is preferably arranged on thesecond separating element on the side facing away from the firstseparating element or the side with the separating element outer wall inorder to support the second separating element against a pressure whichacts on the separating element inner wall. The separating element outerwall thus forms a first end side of the rib structure. The opposite orsecond end side of the rib structure is formed by the structure end sidewhich is preferably configured to be planar. The structure rib is acarrying element of the supporting rib structure and extends from theseparating element outer wall to the structure end side. As a result ofthe supporting function of the rib structure, the brake system dampingdevice is itself stable. The material of the second separating elementis furthermore put under less load, which has a positive effect on itsservice life.

The rib structure is preferably configured with two or more structureribs in order to give the rib structure further stability. Moreover, therib structure is advantageously formed with a vertical circular hollowcylinder which is positioned centrally on the separating element outerwall and extends therefrom up to the second end of the rib structure orthe structure end side. A cylinder cavity formed in the circular hollowcylinder is preferably connected to the passage in the second separatingelement in a medium-conducting manner. At this point, it should beexplicitly pointed out that the passage in the second separating elementcan in no event be closed by the rib structure.

The structure ribs are positioned externally on the circular hollowcylinder and have at these points—referred to below as startingpoints—an extension or rib depth which corresponds to the length of thecircular hollow cylinder. The structure ribs preferably extend fromthese starting points radially or in a radiant manner away from thecircular hollow cylinder, as a result of which a star-shaped structureis created. In this case, the rib depth of each structure rib varies inaccordance with the form of the bearing end sides of the rib structure.As already mentioned, the structure end side is preferably planar andtherefore does not cause any variation in rib depth. The separatingelement outer wall in contrast is usually configured to be uneven orthree-dimensional. The respective rib depth must then vary or beconfigured in accordance with the separating element outer wall. Thestability of the rib structure is further improved as a result of this.

The rib structure preferably forms at least two structure sub-chamberswhich are connected to one another by means of at least one connectingchannel in a medium-conducting manner. The structure sub-chambers areformed in each case by means of at least one structure rib, theseparating element outer wall and a further component which surroundsthe third chamber. This component is, as already mentioned above,preferably the cover. The structure sub-chambers are preferably arrangedsuch that a supporting rib structure is generated or the supportingeffect of the rib structure is further reinforced. The connectingchannel is an opening in an element, preferably a structure rib, whichseparates the two structure chambers from one another. In this manner,the compressible medium travels from the second chamber into each of thestructure sub-chambers of the divided third chamber and a maximumdamping thus arises for the brake system damping device. A lower degreeof damping can, however, also be set by means of sealing off individualstructure sub-chambers or closing individual connecting channels, wheredesired.

If the rib structure is configured with the circular hollow cylinder, asdescribed above for one advantageous embodiment, a connecting channelpreferably leads from this cylinder cavity to each of the structuresub-chambers. In this manner, a uniform spread of the medium and thus aneven loading of all regions of the rib structure can be achieved.

As already mentioned above, the compressible medium is preferablyconfigured as a gas, and particularly preferably as air. Therefore,below, the third chamber is also referred to as a second air chamber,the structure sub-chambers are also referred to as air sub-chambers andthe medium volume is also referred to as an air volume. Accordingly, thesecond air chamber was replaced by several connected air sub-chamberswhich take up an air volume, wherein a desired graduated damping of thebrake system damping device can be adjusted by means of the airsub-chambers. In other words, the proposed design offers configurationpossibilities for the connection of the air chambers by means of theconnecting channels.

Moreover, the second separating element is not only provided to separatethe second chamber from the third chamber or from the second airchamber, but also preferably fulfils a holding or carrying function forthe first separating element. The first separating element is, asalready mentioned above, advantageously configured with a diaphragm. Thesecond separating element is therefore also referred to below as thediaphragm carrier component. An inherently stable diaphragm carriercomponent which also offers several configuration possibilities of thethird chamber or its separation is generated by means of the describedrib structure. The described configuration of the diaphragm carriercomponent furthermore allows the use of low-cost mold-dependentcomponents which can be produced, for example, by means of technologiessuch as injection molding.

In a further advantageous embodiment, the rib structure has a rib jacketwhich is configured to surround the rib structure and in particular witha jacket outer wall and a jacket inner wall. The rib jacket is a type ofhollow cylinder which encloses the rib structure and extends from theseparating element outer wall up to the structure end side. The jacketouter wall bears against the component surrounding the third chamber.The jacket inner wall forms a surface up to which the structure ribsextend. With the rib jacket, the rib structure is configured to be morecompact and even more stable.

The rib structure and the rib jacket are preferably configured in onepiece, preferably in one piece with the second separating element. Inone piece means, as already mentioned, that several elements, here therib structure with the rib jacket, and preferably also with the secondseparating element are formed in one piece or as one part. The advantagehere lies in simple assembly and low-cost production.

Moreover, the rib jacket is according to the disclosure advantageouslyconfigured with at least one jacket slot, wherein the jacket slot isarranged preferably extending from the structure end side in thedirection of the separating element outer wall and provided to open therib jacket toward one of the structure sub-chambers. The jacket slotstherefore form recesses in the otherwise fully closed rib jacket. Thevolume which can be taken up for the compressible medium is increased bymeans of these recesses or cavities, as a result of which the degree ofdamping of the brake system damping device is increased. Material isalso saved.

The rib jacket is furthermore preferably configured with at least onelatching element, wherein the latching element is arranged preferablyprojecting from the jacket outer wall and preferably on the structureend side. The latching element is a nub or hook which is provided tolatch into a recess within the component which surrounds the jacketouter wall. The latching element thus offers the possibility ofanchoring the second separating element in the third chamber. The brakesystem damping device gains additional stability as a result of this.

Building on this, the latching element is arranged bearing against twojacket slots. The two jacket slots lead in each case directly along thelatching element, as a result of which a flexible or compressiblecarrier apparatus is formed for the latching element. The secondseparating element can thus be mounted more easily or lead to alatching-in position. Particularly if the second separating element isproduced from a material which can only be deformed with greatdifficulty, its assembly is significantly facilitated by means of theformed carrier apparatus.

According to the disclosure, the brake system damping deviceadvantageously has a component which encompasses the rib jacket with acomponent inner wall in the case of which the component inner wall isconfigured with a recess which runs around the jacket outer wall,wherein the recess is provided to latch in the latching element. Thecomponent is preferably the cover or the housing of the brake systemdamping device. The component inner wall or a surface of the componentwhich bears against the rib jacket or its jacket outer wall forms,together with the latching hooks arranged on the jacket outer wall, apositive-locking connection between the second separating element ordiaphragm carrier component and the surrounding component, preferablythe cover. The recess is preferably the depression described above.Since the recess is formed circumferentially in the circumferentialcomponent, but the at least one latching element is in contrastconfigured individually, this positive-locking connection is flexibleand position-independent in relation to the latching element.

The structure end side is furthermore arranged bearing against thecomponent inner wall in order to be supported thereon. Bearing againstthe component inner wall increases the supporting effect of the ribstructure and significantly reduces the surface pressure on thecomponent inner wall, preferably the cover. As a result of this, softerand/or lower cost materials can also be used instead of very solidmaterials, such as preferably composed of machined metal, for thediaphragm carrier component or the second separating element. Expedientmold-dependent components can also thus expediently be used as adiaphragm carrier component.

In one advantageous embodiment, the second separating element isproduced by means of injection molding, preferably by means of powderinjection molding and particularly preferably by means of metal-powderinjection molding. Injection molding, also referred to as an injectionmolding process, is a manufacturing process, to be more precise acasting process for the production of components. In this case, therespective material is liquefied with an injection molding machine andinjected into a mold under pressure. Powder injection molding, alsoreferred to as the PIM method, is a casting process for the productionof components composed of metal or ceramic. Consequently, metal-powderinjection molding, also referred to as the MIM method, is a castingmethod for the production especially of metal components. The secondseparating element or the diaphragm carrier component can be producedvery easily and at low cost as a mold-dependent component by means ofthese technologies.

In one advantageous further development of the disclosure, the brakesystem damping device has a fourth chamber which is arranged to surroundthe rib jacket of the second separating element in order to additionallyprovide damping volume. The fourth chamber is realized in that thecomponent which surrounds the rib jacket, preferably the cover, isconfigured to be smaller or shorter. The fourth chamber thus forms afurther detachable chamber for additional take-up of medium volume,preferably air volume, without increasing the space requirement withinthe brake system damping device. The larger the available volume is, themore elastic and thus more effective the brake system damping device isin terms of pulsation reduction and damping. This proposed solution thusopens up a possibility of functional optimization without additionaloutlay and costs.

The second separating element is furthermore configured with a bearingring enclosing the rib jacket with a ring outer edge, wherein thebearing ring is arranged projecting into the fourth chamber and bearingagainst the first separating element. The bearing ring bears fixedlyagainst the jacket outer wall of the ring jacket and extends radiallyfrom it, preferably as far as the size of the fourth chamber maximallyallows. The ring outer edge delimits the bearing ring to the outside andpreferably bears against an inner wall of the fourth chamber. With thebearing arrangement of the bearing ring against the first separatingelement, preferably a diaphragm, the fourth chamber is delimited in thedirection of the first separating element and the first separatingelement is supported and stabilized. This also contributes to thestability of the entire brake system damping device. The secondseparating element or diaphragm carrier component thus also forms abearing surface of an externally circumferential sealing region of thefirst separating element, preferably the diaphragm.

The second separating element is furthermore preferably configured inone piece with the bearing ring. Configured in one piece means, asalready mentioned above, that two elements are formed in one piece or asone part, with the advantage of simple assembly and low-cost production.

In a further advantageous further development of the disclosure, atleast one ring rib supporting the bearing ring is arranged on thebearing ring. The ring rib is therefore a carrying or supporting elementwhich is arranged preferably not only bearing against the bearing ring,but also against the jacket outer wall of the ring jacket and/or theinner wall of the fourth chamber. The bearing ring is additionallystabilized as a result of this.

Building on this, there are preferably arranged on the bearing ring twoor more ring ribs with which the fourth chamber is divided into at leasttwo ring sub-chambers. The ring sub-chambers are advantageously formedin each case by means of two ring ribs, the inner wall of the fourthchamber, the jacket outer wall of the ring jacket and the bearing ring.The ring sub-chambers are chambers which use, for their external radialdelimitation, an unchanged interface bore in a component surrounding thefourth chamber, preferably the housing. This new configuration of thesecond separating element therefore forms on its circumferenceadditional ring sub-chambers, preferably air chambers, which can be usedfor further reinforcement and adjustability of the damping.

In a further embodiment, the ring ribs on the jacket outer wall arearranged in each case opposite a structure rib on the jacket inner wall.This arrangement, in the case of which the ring ribs form a type oflengthening of the structure ribs, provides additional stability for thesecond separating element and also simplifies its production.

The jacket slots are preferably arranged in such a manner that theyconnect the third chamber to the fourth chamber in a medium-conductingmanner. By means of this arrangement, the jacket slots act as connectingchannels between the structure sub-chambers in the third chamber and thering sub-chambers in the fourth chamber. In other words, the volume ofindividual surrounding chambers is coupled by means of longitudinalslots, which are also formed on the latching elements, preferablylatching hooks, to the internal volume, preferably air volume, of therib structure. In this manner, the compressible medium travels from thestructure sub-chambers into the ring sub-chambers and the maximumdamping for the brake system damping device thus occurs. Moreover,however, a lower degree of damping can also be set here by means ofsealing off individual ring sub-chambers or closing individual jacketslots, where desired.

According to the disclosure, the at least one ring rib is advantageouslyarranged extending from the jacket outer wall to the ring outer edge ofthe bearing ring. This arrangement effectively exploits the fourthchamber, provides the bearing ring with very high stability and enablesa sealing off between the ring sub-chambers.

In a further advantageous further development of the disclosure, thecomponent encompassing the rib jacket has a component outer wall,wherein the component outer wall is placed in a sealing manner againstthe housing inner wall. The component encompassing the rib jacket is, asalready mentioned above, preferably the cover. In one such preferredembodiment, the imperviousness of the brake system damping device isformed toward the outside between housing and the cover. Theimperviousness of the brake system damping device is thus ensuredparticularly sustainably since none of the components under strainduring braking processes, such as the first or second separatingelement, must contribute to imperviousness.

The component encompassing the rib jacket, preferably the cover, isparticularly advantageously configured and arranged in such a mannerthat the ring ribs of the second separating element are latched-in orlatched in the cover. As a result of this, the component is additionallyfastened or secured in the brake system damping device. The ringsub-chambers are furthermore sealed off from one another better in thismanner.

As a result, the housing inner wall is furthermore preferably placed ina sealing manner against the component outer wall in that the componentencompassing the rib jacket is inserted into the housing by means ofpressing in. Pressing in is a method in which the parts to be connectedare substantially only elastically deformed during joining together andunintentional detachment is prevented by a non-positive connection.Non-positive connections require a normal force on the surfaces to beconnected to one another. Their mutual displacement is prevented as longas the opposite force brought about by the static friction is notexceeded.

The pressing in is preferably carried out by means of a press-infastener. The component encompassing the rib jacket, preferably thecover, would thus have to be configured as a press-in fastener. Thepressing in of a press-in fastener is also referred to as a self-clinchtechnique. Press-in fasteners or self-clinching fasteners areself-sealing or self-closing fastening elements which can be attached tometal sheets, substrates or openings in ductile or deformable materialwithout welding or additional fasteners.

In a further advantageous further development of the disclosure, thediaphragm holding apparatus of the second separating element isconfigured to be spread to the outside in a bead- and/or trumpet-shapedmanner. The first separating element is, as a result of this, fixed moresolidly and imperviously on the housing inner wall. A movement of theclosure element and the diaphragm fold in the direction of the secondseparating element are thus furthermore guided better and a morepositive-locking bearing of the first separating element against theseparating element inner wall of the second separating element isfacilitated.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the solution according to the disclosure areexplained in greater detail below on the basis of the enclosed schematicdrawings. In the drawings:

FIG. 1 shows a first exemplary embodiment of a brake system dampingdevice according to the disclosure,

FIG. 2 shows the brake system damping device in FIG. 1 in the case of afirst applied hydraulic pressure,

FIG. 3 shows the brake system damping device in FIG. 1 in the case of asecond applied hydraulic pressure,

FIG. 4 shows a diagram with characteristic lines as a function ofpressure and volume take-up in brake system damping devices and

FIG. 5 shows a second exemplary embodiment of a brake system dampingdevice according to the disclosure,

FIG. 6 shows a third exemplary embodiment of a brake system dampingdevice according to the disclosure in three first steps of its mounting,

FIG. 7 shows the exemplary embodiment according to FIG. 6 in two furthersteps of its mounting, and

FIG. 8 shows the exemplary embodiment according to FIG. 6 in two laststeps of its mounting.

DETAILED DESCRIPTION

A brake system damping device 10 having a housing 12 and a cover 14 isrepresented in FIG. 1. There is arranged in housing 12 a supply line 16,in which in the present case no hydraulic pressure is applied,represented by means of a crisscrossed arrow 18. Supply line 16discharges into a first chamber 20 which adjoins a first separatingelement 22, here a roller diaphragm. As seen from first chamber 20, asecond chamber 24 is located behind first separating element 22, whichsecond chamber 24 is adjoined by a second separating element 26, whereinin the direction of view a third chamber 28 is located behind secondseparating element 26.

As seen in detail, these chambers 20, 24, 28 and separating elements 22,26 have the following appearance. First chamber 20 is surrounded by ahousing inner wall 30 and a first separating element inner wall 32 offirst separating element 22, referred to below as a roller diaphragm. Aclosure element 34 from which separating element 22 extends further tothe outside to a diaphragm fold 36 is arranged to be formed centrally inseparating element 22 and formed in one piece with it. A diaphragm foldrecess 38 is located within diaphragm fold 36 or is surrounded by it.Adjoining diaphragm fold 36, separating element 22 extends up to adiaphragm collar 40 which engages around a coupling rim 42 of housing12. Separating element 22 configured as a roller diaphragm bears with apart of its separating element inner wall 32 in a sealing manner againsthousing inner wall 30, and faces toward second chamber 24 with a firstseparating element outer wall 44. Second chamber 24 is surrounded byfirst separating element outer wall 44 and a second separating elementinner wall 46 of second separating element 26.

Second separating element 26 extends with a diaphragm retainingapparatus 48 into diaphragm fold recess 38. A passage 50 which connectssecond chamber 24 to third chamber 28 is arranged centrally in secondseparating element 26. Passage 50 is guided through second separatingelement inner wall 46, second separating element 26 and a secondseparating element outer wall 52. Third chamber 28 is surrounded bysecond separating element outer wall 52 and a cover inner wall 54 ofcover 14.

In the represented starting state of brake system damping device 10, nohydraulic pressure is initially applied in first chamber 20 in which abrake medium is located. Separating element 22, which is produced froman elastomer, is therefore located here substantially in its basic form.In this case, it bears against housing inner wall 30 in such a mannerthat first chamber 20 is hermetically sealed off from second chamber 24,wherein a gas, here specifically air, is located in second chamber 24.This gas is also located in third chamber 28 which is connected tosecond chamber 24 by means of passage 50. Both chambers 24, 28 thus forma joint gas volume available for damping. As a result of the greaterelasticity of this gas volume, a better damping action is achievedduring braking or when applying a hydraulic pressure on first chamber20.

If a hydraulic pressure is applied in first chamber 20, separatingelement 22 deforms in such a manner that the gas volume in secondchamber 24 is reduced. Closure element 34 moves into second chamber 24.From a specific hydraulic pressure which is set above a pressure rangewhich is relevant for damping, closure element 34 bears against secondseparating element inner wall 46 of second separating element 26 andcloses passage 50 to third chamber 28. Second separating element 26 actslike a stop here. States of brake system damping device 10, in the caseof which separating element 22 or closure element 34 thereof againstsecond separating element 26 and closes passage 50, are represented inFIG. 2 and FIG. 3.

As a result of closed passage 50, third chamber 28 is thus separatedfrom second chamber 24, as a result of which only the remaining gasvolume in second chamber 24 can be used for the further damping. Theelasticity and damping action is only small since second chamber 24 isbarely able to take up further volume. This effect is intentional sincethe travel of a brake pedal connected to the brake system is thus alsono longer significantly lengthened. In the case of the state representedin FIG. 3 of brake system damping device 10, separating element 22 andsecond separating element 26 bear seamlessly or across the full surfaceagainst one another so that second chamber 24 disappears entirely or hasno volume any more. In this case, the travel of the brake pedal is nolonger lengthened.

As soon as the hydraulic pressure applied in first chamber 20 decreases,separating element 22 moves back into its starting state or its startingposition.

FIG. 2 shows brake system damping device 10 from FIG. 1, but in a statein the case of which a first hydraulic pressure is applied on firstchamber 20, represented by means of an arrow 56 in the region of supplyline 16.

As already mentioned, closure element 34 bears against second separatingelement inner wall 46 of second separating element 26 and closes passage50 to third chamber 28. Only the remaining volume in second chamber 24can thus be used for the further damping. In the representation of FIG.2, this is primarily the region around diaphragm retaining apparatus 48.The effects on the damping and the braking process have already beenlisted in detail in the description relating to FIG. 1 and are thereforenot described again here.

FIG. 3 represents brake system damping device 10 from FIG. 1, but in astate in which a second hydraulic pressure is applied on first chamber20, represented by means of an arrow 58 in the region of supply line 16.

As already mentioned, closure element 34 bears against second separatingelement inner wall 46 of second separating element 26 and closes passage50 to third chamber 28. Separating element 22 and second separatingelement 26 furthermore bear seamlessly against one another so thatsecond chamber 24 no longer has any volume. The effects associated withthis on damping and the braking process have already been listed indetail in the description in relation to FIG. 1 and are therefore notdescribed again here.

FIG. 4 shows a diagram of the relationship between a pressure 60 and avolume take-up 62 in such brake system damping devices. Here, pressure60 is plotted on the x-axis and volume take-up 62 is plotted on they-axis. A first characteristic line 64 and a second characteristic line66 extend from a coordinate origin of the diagram. The diagram alsoshows a vertical, dashed line 68 which intersects the x-axis and ahorizontal, dashed line 70 which intersects the y-axis.

First characteristic line 64 shows the relationship between pressure andvolume take-up for a brake system damping device with a small volume ofmedium which is available for damping. For the sake of simplicity here,the volume of second chamber 24 in FIG. 1 is assumed for saidcharacteristic line 64.

Second characteristic line 66 which extends above first characteristicline 64 shows the relationship between pressure and volume take-up for abrake system damping device with a comparatively large volume of mediumwhich is available for damping. For the sake of simplicity, the totalvolume of second and third chamber 24, 28 in FIG. 1 is assumed here forcharacteristic line 66.

A predefined pressure value 68 which forms the upper limit of a pressurerange which is relevant for pulsation damping in such brake systems isrepresented with vertical, dashed line which intersects the x-axis. Thisrelevant pressure region thus extends from the coordinate origin up tothe dashed line.

A volume stop 70 for brake system damping device 10 according to thedisclosure is represented with the horizontal, dashed line whichintersects the y-axis. This volume stop lies approximately at the volumeof second chamber 24 in FIG. 1.

By means of corresponding configuration of the respective volumes ofsecond and third chamber 24, 28, brake system damping device 10 ismatched to the relevant pressure range and the desired elasticity ordamping action in this pressure range. In the case of optimum matching,as represented in the diagram of FIG. 4, dashed lines 68, 70 intersectwith characteristic line 66 at a point.

FIG. 5 represents a brake system damping device 10 which differs fromthat in FIG. 1 only in the region in which first separating wall 22configured as a roller diaphragm faces with first separating elementouter wall 44. Separating element 22 itself and the region whichseparating element 22 faces with first separating element inner wall 32correspond entirely with FIG. 1, and are not described again here.

The main difference from brake system damping device 10 in FIG. 1 isthat, instead of third chamber 28 and associated passage 50 in FIG. 1,brake system damping device 10 here in FIG. 5 has a first sub-chamber 72with a passage 74 and a second sub-chamber 76 with a second passage 78.The two sub-chambers 72, 76 are separated by means of a separating wall80. A further difference to FIG. 1 lies in second separating element 26extending up to housing inner wall 30 here in FIG. 5 and separatingcover 14 from it.

All of the further features correspond to those in FIG. 1. Secondchamber 24 is thus also surrounded here by first separating elementouter wall 44 and a second separating element inner wall 46 of secondseparating element 26. Second separating element 26 also extends herewith a diaphragm holding apparatus 48 into diaphragm fold recess 38 ofseparating element 22. Moreover, sub-chambers 72, 76 are next toseparating wall 80, like third chamber 28 in FIG. 1, surrounded bysecond separating element outer wall 52 and a cover inner wall 54 ofcover 14.

The mode of operation here is similar to brake system damping device 10in FIG. 1. If a hydraulic pressure is applied in first chamber 20,separating element 22 also deforms here such that the gas volume insecond chamber 24 is reduced. Closure element 34 moves into secondchamber 24 and, from a specific hydraulic pressure which ideallycorresponds to the upper limit of the relevant pressure region bearsagainst second separating element 26 and closes passages 74, 78 tosub-chambers 72, 76.

As soon as the hydraulic pressure applied in first chamber 20 isreduced, separating element 22 configured as a roller diaphragm movesback into its starting state or its starting position. As a result ofthis, passages 74, 78 are then opened again and sub-chambers 72, 76 areconnected again to second chamber 24.

FIGS. 6 to 8 illustrate an exemplary embodiment of a brake systemdamping device 10 in the case of which the second separating element 26is likewise configured with a passage 50 and sub-chambers 72 and 76 bymeans of at least one separating wall 80. The second separating element26 is furthermore configured, at its jacket outer wall 82 of the thirdchamber 28, such that said second separating element forms a fluid-tightinterference fit 84 with the cover 14 there.

In the case of the brake system damping device 10 as per FIGS. 6 to 8,it is furthermore the case that the first separating element 22 and thesecond separating element 26 and also the cover 14 are to bepreassembled to form an assembly 86 in which the first and secondseparating elements 22, 26 extends along an axis 88 and the firstseparating element 22 is covered radially on the outside at least incertain portions by means of a hollow cylindrical sleeve 92, which ispushed onto the first separating element 22.

FIG. 6 shows, on the left, the cover 14 and, in the center, the secondseparating element 26 pre-mounted thereon by means of the interferencefit 84. Furthermore, FIG. 6 shows, on the right, the first separatingelement 22 pre-mounted onto the second separating element 26 and ontothe cover 14. Here, the cover 14 and the first separating element 22fully enclose the second separating element 26. It is also possible inFIG. 6 to see the two chambers 24 and 28 thus formed. Furthermore, onthe first separating element 22, it is possible to see the diaphragmcollar 40 thereof and also a sealing bead 94, by means of which thefirst separating element 22 seals radially at the outside against thesecond separating element 26 and axially against the cover 14.

FIG. 7 shows the in this case hat-shaped sleeve 92 and the mountingthereof on the preassembled assembly 86 composed of cover 14, secondseparating element 26 and first separating element 22. The sleeve 92 hasa substantially hollow cylindrical jacket wall 96, which extends in anaxial direction, and a shoulder 98, which, to the left of said jacketwall as seen in FIG. 7, projects substantially in a radial direction. Atthe transition from the jacket wall 96 to the shoulder 98, there isformed a radially internal first insertion bevel 100. Said insertionbevel 100 facilitates the pushing of the sleeve 92 onto the firstseparating element 22 and, there, in particular onto the sealing bead 94(see FIG. 7, left). With the pushing of the sleeve 92 onto the sealingbead 94, the latter is forced radially against the second separatingelement 26 and also axially against the cover 14 in order to seal influid-tight fashion there. The insertion bevel 100 furthermore alsofacilitates the further pushing of the sleeve 92 with the jacket wall 96thereof radially at the outside onto a collar portion 102, whichencompasses the second separating element 26 at its jacket outer wall82, of the cover 14 (see FIG. 7, right). The sleeve 92 is pushed ontothe assembly 86 until said sleeve comes to bear with its shoulder 98against the cover 14.

Finally, FIG. 8 illustrates how the assembly 86 is to be mountedtogether with the sleeve 92 into the housing 12. Here, it can be seenthat the sleeve 92 is equipped, at its end region, facing toward thehousing 12, of its jacket wall 96, with a radially external secondinsertion bevel 104, by means of which the insertion into the bulge,which forms the chamber 20, of the housing 12 is facilitated. As theassembly 86 is inserted together with the sleeve 92, the envelopesurface 90 thereof simultaneously protects the first separating element22 with its sealing bead 94 against damage owing to friction along thehousing inner wall 30 (see FIG. 8, left). At the same time, aforce-fitting interference fit 106, which seals in fluid-tight fashion,is formed between the envelope surface 90 and the housing inner wall 30.

As the last step of the mounting, cover 14 is fixed externally onhousing 12 by means of a caulking 108 and in this manner the arrangementof first separating element 22, second separating element 26, cover 14and sleeve 92 is arranged in housing 12 in a stationary manner (see FIG.8, right).

What is claimed is:
 1. A brake system damping device, comprising: afirst chamber on which hydraulic pressure is to be applied; a secondchamber in which a compressible medium is located; a first separatingelement configured to separate the first chamber from the secondchamber; a third chamber in which a compressible medium is located; asecond separating element configured to separate the second chamber fromthe third chamber, the second chamber connected to the third chamber ina medium-conducting manner by a passage configured in the secondseparating element; and a closure element configured to be moved withthe first separating element, the passage configured to be closed by theclosure element as soon as the hydraulic pressure in the first chamberhas reached a predefined pressure value, wherein the first separatingelement and the second separating element are configured to bepreassembled to form an assembly in which the first and secondseparating elements extend along an axis and the first separatingelement is covered radially on the outside at least in certain portionsby an envelope surface.
 2. The brake system damping device as claimed inclaim 1, wherein the envelope surface is formed by a hollow cylindricalsleeve disposed on the first separating element.
 3. The brake systemdamping device as claimed in claim 1, wherein the envelope surface isconfigured with a radially external interference fit configured to pressinto a housing that receives the assembly.
 4. The brake system dampingdevice as claimed in claim 1, wherein the envelope surface is configuredwith a radially internal first insertion bevel configured to facilitatepushing of the envelope surface onto the first separating element. 5.The brake system damping device as claimed in claim 1, wherein theenvelope surface is configured with a radially external second insertionbevel configured to facilitate insertion of the envelope surface into ahousing that receives the assembly.
 6. The brake system damping deviceas claimed in claim 1, wherein the envelope surface is configured with aradially external shoulder configured for support on a housing thatreceives the assembly.
 7. The brake system damping device as claimed inclaim 1, wherein the second separating element is supported by a coverthat simultaneously delimits the third chamber.
 8. The brake systemdamping device as claimed in claim 7, wherein the second separatingelement is fully enclosed by the cover and the first separating element.9. The brake system damping device as claimed in claim 1, wherein thefirst separating element has an annular sealing bead that bears in asealing manner against the second separating element.
 10. The brakesystem damping device as claimed in claim 1, wherein the firstseparating element is formed in one piece with the closure element. 11.The brake system damping device as claimed in claim 1, wherein the firstseparating element is configured with a diaphragm.
 12. The brake systemdamping device as claimed in claim 1, wherein the first separatingelement is produced from an elastomer.
 13. The brake system dampingdevice as claimed in claim 2, wherein the hollow cylindrical sleeve ispushed onto the first separating element to form the envelope surface.14. The brake system damping device as claimed in claim 9, wherein theannular sealing bead bears against a cover that supports the secondseparating element.
 15. The brake system damping device as claimed inclaim 11, wherein the diaphragm is a roller diaphragm.
 16. The brakesystem damping device as claimed in claim 12, wherein the elastomer isethylene propylene diene rubber.